The search for life beyond Earth has been one of the most driving forces behind interplanetary missions and the most successful venture has been around Jupiter and its moons. Among the 53 moons circling Jupiter, one is primed with data suggesting the presence of watery oceans under their surface, indicating there is the likely stuff of life out there.

As Nasa prepares to launch the ambitious Europa Clipper mission towards Jupiter’s Moon of the same name, the mission will go deeper into the secret of possible watery plumes ejecting from the surface of the ice-covered ocean world. The spacecraft will study the moon from its deep interior to its surface to determine whether it has ingredients that make it a viable home for life.

Scientists have said that Europa is geologically dynamic, generating heat inside as their solid layers stretch and flex from the gravitational tug-of-war with their host planet and neighbouring moons. It is not the heat of the Sun that keeps subsurface water from freezing on these ice-covered moons, instead, it’s this heat generated from inside that could have stopped the freezing under the surface.

EUROPA’S MYSTERIOUS WATER PLUMES

Scientists using the Galileo spacecraft, Hubble Space Telescope, and large Earth-based telescopes have reported detections of faint water plumes or their chemical components at Europa. However, no one is certain about the event.

“We’re still in the space where there’s really intriguing evidence but none of it is a slam dunk,” said Matthew McKay Hedman, a member of Europa Clipper’s Mapping Imaging Spectrometer for Europa (MISE) science team. These plumes, when studied by the Europa Clipper spacecraft, could offer insights into the interior layers of the moon.

“It all comes down to whether Europa is habitable, and that comes down to having some understanding of what is happening below the surface, which we can’t reach yet,” Shawn Brooks, who is working with Europa Clipper’s Europa Ultraviolet Spectrograph (Europa-UVS) science team told Nasa.

EUROPA NOT ALONE WITH POTENTIAL SIGNS OF HABITABILITY

Scientists had first observed these mysterious plumes erupting from the surface of Saturn’s moon Enceladus in 2005. The giant column of vapour, ice particles, and organic molecules spraying from the moon’s south polar region suggested that there’s a liquid water ocean below Enceladus’ ice shell and confirmed the moon is geologically active.

These plumes thrust Enceladus and other worlds in the outer solar system, with no atmospheres and far from the heat of the Sun, toward the top of Nasa’s list of places to search for signs of life. “A lot of people think Europa is going to be Enceladus 2.0, with plumes constantly spraying from the surface. But we can’t look at it that way; Europa is a totally different beast,” Lynnae Quick, a member of the science team behind Clipper’s Europa Imaging System (EIS) cameras said.

Europa is different from Enceladus since it is much closer to Jupiter than Enceladus is to Saturn. More heat is generated at the moon from friction produced as it circles its host planet. “Given that internal heat stimulates geological activity on rocky worlds, Europa is expected to have more extensive geology than Enceladus,” Nasa said.

WHAT IS THE EUROPA CLIPPER MISSION?

The Europa Clipper mission is preparing to conduct the first dedicated and detailed study of an ocean world beyond Earth. The probe will determine if this distant moon has conditions favourable for life. The expedition’s objective is to explore Europa to investigate its habitability.

The spacecraft is not being sent to find life itself, but will instead try to answer specific questions about Europa’s ocean, ice shell, composition and geology. Europa was first discovered by Gallileo in 1610, who also found three other moons, Ganymede, Callisto and Io, around Jupiter.